Friday, April 9, 2010

Using Perl modules

  • Let the first line in the .pm file be package Red::Green::Blue;.
  • The .pm file should be named
  • The .pm file must be stored at dir/Red/Green/
  • In the perl program where you want to use this module, include use lib "dir";. This tells Perl to also look in dir when searching for modules. (this basically adds an entry to @INC).
  • In the same program, after the previous line, include use Red::Green::Blue;. This tells Perl to find path/Red/Green/ for all paths in @INC, including dir.
When this will not work -
  • If you get the error Can't locate loadable object for module qwe, then the module is a non-pure Perl module and uses external code (e.g. C code), which should come in a .so file.
  • The easy way is to do sudo cpan Red::Green::Blue and install the module.
  • If you do this, sure to remove the file dir/Red/Green/ so that Perl does not use it instead of the installed module.